WASHINGTON — Sandy wasn’t always a big bully. For several days, this looked like a “kind of boring” hurricane, said NOAA meteorologist Ian Sears, who flew into the storm three times in a hurricane hunter airplane. Then came Friday night, nearly three days before landfall in New Jersey, when the cold front chugging west hooked up with the tropical system steaming north.
It wasn’t a marriage of equals.
Sandy “was surrounded and absorbed as much as merged,” Franklin said.
Suddenly, everything changed. Sandy wasn’t getting its energy from warm water below like a normal hurricane but was being fueled from above. The strongest winds were about 100 miles to the west of the storm’s center, something quite un-tropical.
That moment “was absolutely critical,” said Jeff Masters, director of meteorology at Weather Underground and a former hurricane hunter meteorologist. “You had a wind field that more than doubled in less than one day. That’s a huge amount of power to put in one storm.”
Sandy kept growing. Its band of tropical-storm-force wind stretched for a record 1,000 miles, nearly the distance from New York to Orlando. The size was “one of the biggest factors in the unusually large amount of surge in the New Jersey and New York coastline,” said Jamie Rhome, the hurricane center’s chief for storm surge.
One way to measure a storm’s strength is how low the barometric pressure drops. When Sandy made landfall, it nearly set the record for the lowest central pressure measured north of the Mason-Dixon line in the United States.
A NOAA experimental program measured Sandy’s “destruction potential” for waves and surge at a record-high 5.8 on a 6-point scale. Masters said that meant Sandy’s winds “had the energy of five Hiroshima-sized A-bombs.” It was a “Godzilla-like beast of a storm,” he said.
When Sandy combined with a second cold front, it regained some of its lost power. That’s when Sandy went “from ginormous to mega-normous,” said hurricane center specialist Eric Blake, who wrote the agency’s final 157-page report dissecting what made Sandy tick.
But more importantly, the second merger took the storm away from a path that would likely have curved harmlessly away from the coast. Instead, it triggered a sharp left turn into New Jersey. That meant a worst-possible scenario with the storm pushing water in a direct perpendicular hit into land through a sheltered harbor, concentrating the surge as if it were being forced through a funnel, surge expert Rhome said.
While tropical storms do sometimes reach New Jersey, they rarely make that sharp westward turn. Columbia University professor Adam Sobel, who has studied Sandy extensively, ran computer models that show it should happen only once in 700 years. They usually hit from the south, as did Hurricane Irene when it landed in Brigantine, N.J., in 2011, a direction that doesn’t maximize the surge like Sandy’s punch from the east. Though Irene caused billions of dollars in damage mostly in inland flooding, it didn’t live up to its billing in the New York metro area; many New Yorkers may have downplayed Sandy because of their Irene experience.
Sandy made landfall, oddly enough, in Brigantine, slamming in from a different direction so the surge was far worse. It technically reached New Jersey as a “post-tropical cyclone,” not a hurricane, but that distinction means little. It was a monster.
“Look at Sandy as a whole, the fact that you had a blizzard associated with a major (tropical) event that set record surges in New York Harbor, that destroyed part of the New Jersey coast, that had record waves and surges in Lake Michigan,” National Weather Service director Louis Uccellini said. “All those things combined really made this a unique system.”
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